Identification system requiring momentary contact by limb-worn ID unit with reader detector array

ABSTRACT

An environmentally tolerant personal identification, access control and monitoring system including a dual contact limb-worn identification (ID) code-producing unit and a multiple-physical contact arrayed ID code reader are described. Momentary physical contact between the unit&#39;s dual contacts, in any position and orientation, and the reader&#39;s arrayed multiple contacts is detected by sequentially energizing contact pairs of the array until a characteristic low-impedance is sensed and then the indicated contact pair is reverse-energized to read the ID code from the ID unit. Preferably, the contact array geometry is of closely spaced, nickel-plated, planar, hexagonally shaped conductors that are group-encoded and -energized to minimize the input/output port requirements of a microprocessor and associated drive/sense electronics that accomplish the scanning of the array and the reading of the ID unit. False-positive indications of physical contact by an ID unit are avoided by the preferred sensing method, which can distinguish therefrom a condition in which adjacent contacts in the array incidentally are bridged, e.g. by a buildup of ice on the ID reader&#39;s contact array. ID codes may be used to collect person-tracking information, as well as to limit access to a person wearing a properly encoded ID unit.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates generally to personal identification (ID), accesscontrol and monitoring systems involving an ID reader and an ID unitresponsive thereto for ID code processing and verification. Moreparticularly, the invention relates to a system involving position- andorientation-tolerant, physical contact between a two electrical contactID unit preferably worn on the person and a multiple electrical contactID unit detector and ID reader, the system having been found to beparticularly effective in controlling and monitoring the whereabouts ofsnow skiers.

Prior art ID, access and inventory control systems involve variouscontact and non-contact configurations in which an article or personpasses a checkpoint and it is identified and/or is allowed or deniedentry based on predetermined control criteria. Exemplary of anon-contact system are point-of-sale bar-code readers used inmerchandising outlets such as grocery stores by which purchased articlesare identified, priced and inventory-controlled. Exemplary of a contactsystem are magnetic card readers used in secure facilities that verifythe authority of a cardholder to enter or depart a controlled area bywhich a lock on a door automatically may be released and failing whichentry is denied. These and other systems rely upon the controlledmanipulation of an article carrying the identifying marks, whether it bea purchased article or a card. Such systems are error-prone, even in therelatively controlled environments in which they typically are found,because they depend upon some form of radio frequency (RF) signal,optical, magnetic or acoustic coupling through a medium such as airbetween the ID-encoded media and the media reader.

In harsh environments such as snow ski areas, where moisture, sub-zerotemperatures and electromagnetic interference (EMI) from nearby skilifts have rendered access control and monitoring systems particularlyunreliable, there is yet a need reliably to control access to lifts andto monitor the whereabouts of skiers. Skiers of different sizes and skilevels--all subject to cold weather and laden with clothing and skiequipment that restricts their mobility and dexterity--must passcheckpoints, e.g. ski lift entry points, to gain access to the slopes.While they tend to relieve the skier of this volitional burden,mechanical systems by which, for example, a lift ticket is verified andpunched or a bar code thereon is read by a wand are ski resort stafflabor-intensive. Automatic ID scanning systems that attempted to utilizeRF, optical, acoustic or magnetic coupling or telecommunication betweenan ID-encoded medium and an ID medium reader would be subject to thereliability problems described above, which problems would be heightenedby environmental concerns.

Accordingly, it is a principal object of the present invention toprovide an automatic personal ID, access control and monitoring systemsuitable for use in harsh environments such as snow ski areas.

Another important object of the invention is to provide such a systemthat imposes no unreasonable requirements or constraints on a snowskier.

Yet another object is to provide such a system that includes a wearableID-encoded unit having two electrical contacts and an ID reader havingmultiple, two-dimensionally arrayed electrical contacts whereby thelatter provides a large-area target for the casual skier to impact withthe ID-encoded unit contacts.

An also important object is to provide such a system that is capable ofreliably verifying a skier's authority to pass a checkpoint regardlessof the position or orientation of the ID-encoded unit.

Still another object of the invention is to provide such a system atreasonable cost.

Briefly summarized, the invention is a personal ID, access control andmonitor system found to be particularly useful in ski lift ticketing andboarding applications. The system in accordance with its preferredembodiment includes a skier limb-worn armband ID device having aconventional integrated circuit (IC) ID code generator and dual spacedelectrical contacts cooperative with a multiple electrical contactdetector array and associated electronics that, upon even momentarycontact by the armband contacts, in virtually any position ororientation, is capable of accurately and reliably reading the IC IDcode and determining by comparison to a computer access control database whether the skier has access authority to a nearby ski lift.

These and other objects and advantages of the invention will be moreclearly understood from a consideration of the accompanying drawings andthe following description of the preferred method and embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an ID unit constructed in accordance withthe preferred embodiment of the invention, of which FIG. 1A shows afragmentary side elevation.

FIG. 2 is an isometric view generally corresponding to that of FIG. 1and showing an ID reader used with the ID unit to read an ID codetherefrom.

FIG. 3 is a schematic block diagram showing the electronics associatedwith the ID reader of FIG. 2.

FIG. 4 is a simplified equivalent circuit diagram illustrating the meansby which the ID reader senses and reads the ID unit.

FIG. 5 is a detailed schematic diagram that illustrates the sense/drivecircuit shown in FIG. 3.

FIG. 6 is a flowchart illustrating a method by which groups of contactswithin the ID reader's contact array may be sensed and read by themicroprocessor shown in FIG. 3.

FIG. 7 schematically illustrates the detailed geometry and group codingof the ID reader's contact array.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a first, portable, preferablyuser-wearable, and in use most preferably limb-worn ID unit 10 is shown.ID unit 10 preferably includes a wrist-, leg- or arm-band 12 suitablyconnected to a housing or substrate 14, which mounts a twin-lead IDcode-producing integrated circuit (IC) 16 (indicated by dashed lines inFIG. 1), a pair of operative leads or terminals 16a and 16b of which areelectrically connected to dual, spaced, electrical, so-called "point"contacts 18a, 18b. Housing 14 and ID IC 16 (including leads 16a and 16b)operatively connected with the pair of spaced contacts 18a, 18b will bereferred to herein as an external-circuit coupler, or circuit-couplingstructure or means, indicated generally at 20.

Point contacts 18a, 18b preferably present small-pattern contact surfaceareas at their distal ends, which extend outwardly and preferably atright angles from housing 14. It has been found to be most effective ifcontacts 18a, 18b are spherically or spheroidally shaped in their distalends, for physically and electrically engaging a code reader to bedescribed by reference to FIG. 2. For best conductivity, durability andmatability, each of contacts 18a, 18b may be of solid brass which istin-plated on proximal end for soldering to one of terminals 16a, 16band which is nickel-plated on the distal end for engaging the codereader. As will be seen, it is the small-pattern contact surface areasof contacts 18a, 18b--relative to the large-pattern planar pluralcontacts array of the code reader--that invokes the "point"characterization of the contacts of unit 10.

IC 16 preferably is a solid-state device providing for the non-volatilestorage (e.g. in a masked or programmable read-only memory (ROM orPROM)) of a code and for its retrieval responsive to defined electricalconditions on operative leads 16a, 16b. IC 16 is capable of producing,in response to a pair of interrogation signals impressed upon leads 16a,16b, a signal bearing a preprogrammed serial number or likeidentification code. A suitable device for use as IC 16 would be devicetype DS2400, which is available from Dallas Semiconductor of Dallas,Tex. in a three-lead, TO-92 package, the third lead (not shown inFIG. 1) of which has no operative connection with the IC's circuitry. Itwill be appreciated that any suitable device 16 may be used that iscapable, when interrogated by a code reader (such as that describedbelow), of producing a signal bearing an identification code, and anysuitable means provided for preferably rigidly mounting the same in suchmanner that it may be intimately associated with, and preferablysecurely attached to, the person, clothing, equipment or accessories ofa user, e.g. a skier.

In accordance with the preferred embodiment of the invention, unit 10includes suitable means, e.g. elastic strap 12, connected with thehousing which mounts circuit coupling structure 20, for extending atleast partially around a limb of a user, as indicated in FIG. 1.Alternatively, it will be appreciated that the housing which mountscircuit coupling structure 20 may be made an integral part of a user'sclothing, e.g. a ski glove or jacket; equipment, e.g. skis or ski boots;or accessories, e.g. an armband, sew-in patch or clip-on badge.Importantly, unit 10 is lightweight and portable, and has its terminals18a, 18b in preferably rigidly maintained, spaced position relative toone another. Preferably, unit 10 is positioned for use relative to theuser in a lateral region of the outerwear or equipment of the user suchthat it may be easily presented when needed for access to a secured areasuch as a ski lift.

Referring briefly to Detail 1A, unit 10 is shown in front elevation andpartial cutaway view to better illustrate its detailed structure.Housing 14 may be seen to have formed therein a cavity 14a, including athrough hole, which accommodates IC 16 and the bodies or posts of pointcontacts 18a, 18b to which terminals 16a, 16b are rigidly connected byany suitable means, e.g. soldering. It will be appreciated that castingcompound may be poured into cavity 14a around these components to sealcircuit coupling structure 20 from environmental elements, with only thedistal ends, preferably between approximately 1/8-inches and 1/4-incheslong, of point contacts 18a, 18b being exposed as shown. Housing 14 alsopreferably is provided with rectangular slots 14b, 14b, which aredimensioned to permit the free ends of elastic strap 12 to be insertedtherethrough and adjusted to an individual user, while securelycapturing the same. Housing 14 preferably has a outer, generally planarsurface 14d adjacent point contacts 18a, 18b for mounting a photographof its authorized user, Which photograph may be securely laminated tothe surface 14d to prevent tampering. Housing 14 may be formed of anysuitable, preferably polymeric material, e.g. it may be injection-moldedplastic.

Turning now to FIG. 2, another, or second, unit 22 interactable withone, or first, unit 10, is shown. Second unit 22 is referred to hereinas a code reader because it is capable of reading the code produced bycode-producing unit 10. Code reader 22 preferably comprises a housing 24and code-reading means including target contact means 26 and associatedelectronics not shown in FIG. 2 but shown in pertinent part in FIGS. 3and 5 (as well as conventional power supply means and power and signaldistribution means such as cables and/or wiring harnesses, not shown).Target contact means 26 includes spaced, plural, generally planar,preferably polygonal contacts such as contact 28 that are arrangedpreferably regularly to form an active sensor expanse, ortwo-dimensional plural contact array, 22a that is disposed on an outer,facing surface of housing 24.

Each contact 28, which is electrically conductive and which may be madeof nickel-plated copper (by processes compatible with the manufacture ofthe double-sided or two-layer printed circuit board (PCB) on whichcontacts 28 preferably are formed, with signal routing to a cableconnector area via lands on the reverse side of the PCB connected tocontacts 28 by properly placed plated-through holes), is electricallyconnected via conventional PCB connectors and cabling with portions of adrive/sense circuit that, as will be seen, is part of electronics 28.Pairs of adjacent contacts 28 are interposed by electrically insulativespaces or gaps 30, thereby forming on expanse 22a a planar,plural-contact grid that acts, in accordance with the invention, as asubstantially extensive target area for engagement by unit 10. As shownin FIG. 2, the collective surface area of plural contacts 28substantially covers the surface of array 22a, while the collectivesurface area of spaces 30 covers only an insubstantial fraction of thesurface thereof.

In accordance with the preferred embodiment, the PCB on which contacts28 are formed has a second layer or circuit clad side including theinterrogation/response signals that energize the contact array and anycircuit coupling structure engaged therewith. In order to prevent thebuildup of ice on outer, exposed expanse 22a, the PCB is heated by a DCsignal that is routed substantially over the entire inner surfacethereof. The serpentine, back-and-forth, elongate path of the heatersignal line preferably is structured to exhibit a 24-Ω resistance (andnegligible inductance), and is energized by a 24-volt DC voltage toproduce approximately one amp of heating current. A heater patternconsisting of 10- or 12-mil parallel lines on 25-mil centers, whereinthe alternate lines are connected on alternate ends thereof to produce asingle, continuous conductive path between ground and the energizing DCvoltage has been found to be effective. Thus, code reader 22 preferablyincludes what may be referred to as means for heating expanse 22a toprevent the buildup of ice thereon that otherwise might result inshort-circuiting between adjacent planar contacts 28.

Planar contacts 28 collectively may be thought of as means defining anactive sensor, response production expanse 22a having plural pairs, e.g.pair 32 indicated by dashed lines in FIG. 2, of spacedexternal-circuit-coupleable response structure, or zones, 32a, 32b eachof which is defined by and is coextensive with a corresponding contact28. Alternatively, planar contacts 28 may be thought of as defining anarray of energizable planar contact pairs. It will be appreciated thatthe inventive code reader system comprises as few as three contacts suchas contact 28 properly dimensioned and arranged (e.g. triangularly) todefine a two-dimensional active sensor expanse having at least two andas many as three pair-wise-couplable response zones any two of whichwould be couplable by an external circuit coupling structure such asstructure 20, as by engagement of point contacts 18a, 18b with activesensor expanse 22a brought about by passing-motion, electrical-physicalcontact therebetween, e.g. by a wearer of ID unit 10 skiing past, andinitiating momentary contact with, code reader 22.

Contact array 22a may be described alternatively as large-target contactmeans which includes spaced, plural, generally planar contacts 28arrayed in two dimensions at least one of which is substantially greaterthan the space L between point contacts 18a, 18b of code-producing unit10. In the preferred embodiment of the invention, contacts 28 arearrayed in two dimensions both of which are substantially greater thansuch space L, as may be seen from FIG. 2, thereby to provide a targetthat is substantially expansive in two dimensions to facilitateengagement anywhere within expanse 22a by point contacts 18a, 18b of IDunit 10. Providing a large target area as described and illustratedrenders it much more convenient for users, e.g. skiers having differentbuilds, agilities and skills, positively to make the slight andmomentary contact that may be necessary to gain access to a securedarea, or to be identified or monitored as to their whereabouts.

Typically, each skier would be equipped with a uniquely serialnumber-identifying ID unit 10, preferably intimately connected with theskier's clothing or equipment and therefore referable to as a garmentitem, and a ski resort would have more than one code reader, or what maybe thought of as an identifying station, 22, used by each skier, andeven the momentary engagement in any of an infinite variety of positionswith the station's response production expanse 22a by the garment itemcompletes a circuit within the identifying station, thereby effectingidentification of the skier, or at least of the garment item worn by theskier, to the station. Thus cooperation between first unit 10 and secondunit 22 operatively couples code-producing means 16 with code-readingmeans, i.e. drive/sense circuitry 46 cooperative with microprocessor 36,so that second unit 22 responds to the coded signal produced by firstunit 10.

It is noted that the given or nominal spacing between point contacts18a, 18b is shown in FIG. 1 as being equal to a distance L. It is notedthat the nominal distance from a given edge portion of a first one ofplural contacts 28 to a non-adjacent corresponding edge portion of anadjacent one of plural contacts 28 also is approximately equal to L, thegiven spacing of dual point contacts 18a, 18b. This relative spacingbetween adjacent contacts of units 10, 22 is important in realizing aprincipal advantage of the invention: unit 10, in substantially anycondition in which each of contacts 18a, 18b even momentarily engagesactive sensor expanse 22a, is operative to complete a circuit withincode reader 22, i.e. effects circuit coupling between at least one pairof couplable response zones 28.

It has been determined that a preferred shape for each of identicallyshaped contacts 28 is that of a regular, or equilateral and equiangularpolygon, e.g. the illustrated hexagon of FIGS. 2 and 7. Other shapes,e.g. squares, equilateral triangles or even circles, may be used tovarious degrees of success in achieving high performance operation ofthe system, which generally is characterized by sensitivity to dualpoint contact by unit 10 and tolerance for incidental bridging. Ahexagon provides superior performance because it achieves a high overallcontact packing density or fill ratio, uniform intercontact spacing anda desirably high ratio (0.866) between the minimum surface dimension(between opposite sides) and the maximum surface dimension (betweenopposite vertices) of each contact. In accordance with the preferredembodiment of the invention, L=0.75-inches and the space betweenadjacent contacts 28 is 0.05-inches, although those of skill willappreciate that any suitable dimensions are possible, and are within thespirit of the invention.

Turning next to FIG. 3, a simplified block diagram of the electronicsassociated with code reader 22 is shown. It will be appreciated thatcertain clocking, gating, latching and buffering details are omitted forthe sake of clarity, which detailed circuitry is conventional and formsno part of the invention. It will also be appreciated that miscellaneousdrive or sense circuitry may be provided in support of auxiliary controlor indication functions. A code reader controller indicated generally at34 preferably includes a microprocessor 36 having at least fourpreferably parallel data input and output ports, a ROM 38 which may beprogrammable, a read-and-write memory (RAM) 40, access controller andindicator logic 42, a serial input/output (I/0) port 44, contactdrive/sense circuitry 46, and contact array 22a. A code comparison table48 (which may simply be a dedicated portion of RAM 40) may be providedif it is desired to locally process identification codes read by codereader 22 to determine whether the user of unit 10 is authorized toaccess the secure area, in which case microprocessor 36 would performcomparisons between the code read from unit 10 and those downloaded intolookup table 48. Alternatively, microprocessor 36 may simply upload to acentral processor (not shown) the codes read from unit 10 for adetermination whether the user's access is authorized.

Data base management techniques may be used to create and maintain database libraries containing identification or serial number informationcorresponding to every ID unit 10 that is lawfully issued, as well asaccess authority and demographic or other useful information regardingthe person to whom the same was issued. In this way, a skier, forexample, wishing to gain access to a ski lift would make passing-motioncontact between both point contacts 18a, 18b of ID code-producing unit10 and contact array 22a of code reader 22, and would either be deniedor granted access via the selective automatic release of a locked gateor turnstile by access controller logic 42, or via the selective manualrelease thereof by ski resort staff who are monitoring aural or visualindicator logic 42. Such data processing and control readily may beaccomplished by conventional techniques such as are commonly known tothose skilled in the art.

FIG. 4 is of a simplified, equivalent circuit that is believed to behelpful in understanding the principle of operation of drive/sensecircuitry 46. A and B represent logic signals that would be controlledindependently, for example, by microprocessor 36 to control the gatesof, and thereby to turn on or off, field-effect transistors (FETs) TA,TB. A logic high voltage level V+ is connected through pull-up resistorsR connected to the sources of common-drain-connected FETs TA, TB. Thesources of FETs TA, TB also are connected as shown to an adjacent pairof planar contacts A', B', which correspond for illustrative purposes tocontacts 28 of code reader 22. Finally, a circuit coupling structureequivalent to structure 20 including ID IC 16 and connected pointcontacts 18a, 18b is shown to be at least momentarily physically andelectrically engaging planar adjacent planar contacts A', B'.

It may be seen from FIG. 4 that if A is pulled low while B is driven orallowed to float high, then with circuit coupling structure 20 (which isroughly equivalent to a diode and thus is characterized by a lowimpedance, when forward biased, relative to the open-circuit impedanceof electrically insulated contacts A', B') engaging adjacent contactpair A', B' in one orientation a low level voltage will appear atcontact B', which could be sensed, for example, by microprocessor 36Alternatively, if B is pulled low while A is driven or allowed to floathigh, then with circuit coupling structure 20 engaging adjacent contactpair A', B' in a second, reverse orientation a low level voltage willappear at contact A', which also could be sensed by microprocessor 36.Thus the engagement of circuit coupling structure 20 with adjacentcontact pair A', B' is sensed regardless of orientation by sequentiallyimpressing on terminals A, B signal pairs defining a first givenpolarity and then a second reverse polarity.

Engagement of an adjacent contact pair A', B' by circuit couplingstructure 20 can be distinguished also from a short-circuit condition,as might be caused by incidental bridging of adjacent contacts A', B',as indicated by a dashed line therebetween. This may be accomplished byfirst determining that a low-impedance condition between contacts A', B'exists, as above described, and then by impressing a reverse polaritysignal pair on the same two contacts A', B'. A short circuit willexhibit a low impedance condition regardless of the polarity of thevoltage impressed on terminals A', B', whereas engagement by circuitcoupling structure 20 will exhibit a low impedance with its internaldiode forward-biased and a high impedance with its internal diodereverse-biased. This abnormal condition, which might indicate a buildupof ice on the contact array of the code reader, may be ignored thusavoiding a false-positive indication of engagement between adjacentcontact pair A', B' and the point contacts of circuit coupling structure20. Upon reversal of the polarity of the signal pair impressed uponterminals A', B' in accordance with this second, conditionally executedstep, circuit coupling structure 20 with the internal diode of IC 16reverse-biased is in its normal operating mode and is ready to be readby code reader 22.

Turning now to FIG. 5, drive/sense circuitry 46 in its preferredembodiment is described. It may be seen from FIGS. 3 and 5 that onlyfour drive/sense paths are provided for all contacts 28 of pluralcontact array 22a. This yields many advantages, in that it significantlyreduces the drive/sense circuitry and signal wire harness requirementsof code reader 22. It also makes it possible to utilize a microprocessorhaving as few as four input and four output (or four common,bidirectional input/output) data ports. In order to detect engagement bycircuit coupling structure 20 anywhere on plural contact array 22a,which as illustrated in FIG. 2 may have thirty-nine or more (or fewer)contacts 28, it is necessary to define groups of contacts 28 and todrive/sense those within the same group in parallel.

In accordance with the preferred embodiment, four groups of contacts aredefined and their arrangement within contact array 22a is optimized in apattern that results in maximal spacing between any two of the samegroup. With this group coding arrangement, the four groups of contacts28 may be driven and sensed, or interrogated, together, in accordancewith the principles discussed above in reference to FIG. 4, in order todetect engagement by circuit coupling structure 20 with a pair ofadjacent contacts 28 anywhere and any orientation within contact array22a. FIG. 5 now straightforwardly may be understood to provide fourdrive signals OUT1-, OUT2-, OUT3-, OUT4- (the - suffix indicatinglow-active signals by positive-true logic conventions) and four sensesignals IN1, IN2, IN3, IN4 corresponding, respectively, to four contactgroups 1, 2, 3, 4 (and indicating the inverse of the logic levels towhich the contact groups are being driven). A drive gate signal DRIVEenables a low-active selected one of drive signals OUT1-, OUT2-, OUT3-,OUT4- when a logic zero to turn on a selected one of four FETs T1, T2,T3, T4 via Schmitt-triggered drive NAND gates N1, N2, N3, N4.

The open drains of common-source connected FETs TI, T2, T3, T4 areconnected in parallel via diodes D1, D2, D3, D4 to V_(DD) and to contactgroups 1, 2, 3, 4 (each of which includes plural contacts that arearranged, as will be described in relation to FIG. 7, in spacedrelationship to one another across expanse 22a), and thus representsignals which, when considered as pairs, may be thought of asrepresenting interrogation signal pairs that are produced byinterrogation signal-producing means--i.e. drive/sense circuitry 46cooperative with microprocessor 36 and a program executing in ROM 38and/or RAM 40--and are impressed on adjacent ones of planar contacts 28of code reader 22 and, with ID unit 10 in engagement therewith, also onpoint contacts 18a, 18b thereof. Four additional diodes D5, D6, D7, D8are connected between the common sources and the drains of FETs T1, T2,T3, T4. Contact groups 1, 2, 3, 4 are connected via resistors R1, R2,R3, R4 to V_(DD) and via resistors R5, R6, R7, R8 to first inputs ofSchmitt-triggered sense NAND gates N5, N6, N7, N8 the second inputs ofwhich are connected in parallel with a sense gate signal SENSE(providing for a self-test mode of operation) to produce IN1, IN2, IN3,IN4, respectively.

Persons skilled in the art will appreciate that associated resistors R1,R2, R3, R4 pull up to a logic one the various first inputs tocorresponding NAND gates N5, N6, N7, N8 so long as the correspondingcontact group 1, 2, 3, 4 is not effectively grounded by the programmedturning on of the corresponding FET T1, T2, T3, T4. Associated resistorsR5, R6, R7, R8 current limit the input voltages to the various firstinputs to NAND gates N5, N6, N7, N8 to protect those logic devices fromtransients or other over-voltage conditions that might be inadvertentlyimpressed on contact groups 1, 2, 3, 4 of contact array 22a.Accordingly, the values of these resistors is not critical and resistorsR1, R2, R3, R4 can be approximately 5-kΩ and resistors R5, R6, R7, R8can be approximately 1.3-kΩ. Within the spirit of the invention, ofcourse, other values may be used. It will also be appreciated thatvariations may be made in the implementation of drive/sense circuitry46, e.g. the threshold voltage determinations may be made by a windowcomparator, Schottky diodes may be used, and other device or topologychanges may be made, without departing from the spirit of the invention.

Those skilled in the art will appreciate that, in accordance with thepreferred embodiment of the invention, signals DRIVE, OUT1-, OUT2-,OUT3-, OUT4-, SENSE may be driven by microprocessor 36 and that signalsIN1, IN2, IN3, IN4 may be sensed by microprocessor 36 in a prescribedsequence, as suggested by the block diagram of FIG. 2. Such a sequenceis controlled by a program residing in ROM 38 and/or RAM 40 theinstructions of which are accessed and executed by microprocessor 36. Ina manner analogous to that described by reference to FIG. 4, the circuitof FIG. 5 is used to poll contact array 22a to detect at least momentarycoupling between contacts of different groups 1, 2, 3, 4 by circuitcoupling structure 20 of ID unit 10. Thus, a given one of OUT1-, OUT2-,OUT3-, OUT4-, e.g. OUT1-, is driven low (active) while all others aredriven or allowed to float high (inactive), and then DRIVE is drivenhigh (active) to enable a selected FET to turn on, or conduct, so thatthe corresponding contact group effectively is grounded. With SENSE high(active), IN1, IN2, IN3, IN4 are sensed by microprocessor 36's readingof the four input data lines for comparison of the sense inputs to thedrive outputs.

If there is no short or circuit coupling structure engagement betweenany contact in contact group 1 and any contact in any other group, thenIN1 should be high (active) and IN2, IN3, IN4 should be low (inactive).If instead there is such a short or such engagement, e.g. involving acontact in group 1 and a contact in group 3, then IN1 would be high(active), IN3 would be high (active) and IN2, IN4 would be low(inactive). In such event, the microprocessor would complement thedriven outputs by driving or allowing OUT1- to float high (inactive) andby driving OUT3- low (active). IN3 should now be high (active) and IN1,IN2, IN4 should be low (inactive). If sensing indicates that IN1 insteadis high (active), then it is concluded that an incidental short-circuitcondition exists between at least one of the contacts in group 1 and atleast one of the contacts in group 3. If instead sensing indicates thatIN1 now is low (active), then it is concluded that circuit couplingmeans 20 not only is engaging at least one contact in group 1 and atleast one contact in group 3, but that it is properly biased so that theidentification code can be read therefrom in accordance withpredetermined pulse amplitude and timing requirements of IC 16.

It will be understood that if circuit coupling means 20 is in a positionof engagement of a contact in group 1 and a contact in group 3 but is inan orientation such that IC 16 is reverse biased, then no circuitcoupling, or closure, will be indicated by the partial polling sequencedescribed above. But a short time later in the polling sequence whenOUT3- is driven low (active) and OUT1-, OUT2-, OUT4- are driven orallowed to float high (inactive), IN1 will sense high (active) ratherthan low (inactive). Then, complementing the drive outputs so that OUT1is driven low (active) and OUT3- is driven or allowed to float high(inactive) will bias IC 16 such that its identification can be read.Thus, in accordance with the preferred embodiment and by the preferredmethod of the invention, the engagement of point contacts 18a, 18b of IDunit 10 in either orientation with adjacent planar contacts 28 is sensedand the code stored therein is read.

Turning now to FIG. 6, a flowchart representing the steps by whichcontact array 22a may be polled by microprocessor 36, the method of theinvention may be better understood. It will be understood, in connectionwith FIG. 6, that J and K are modulo-N and modulo-(N-1) counters thatrepresent one less than the selected contact group number 1, 2, 3, 4(e.g. when J=0, contact group 1 is selected); L represents the logicalcomplement of the state of a given contact group sense input IN1, IN2,IN3, IN4 (and thus the actual state of the corresponding contact group,uninverted by NAND gates N5, N6, N7, N8 of FIG. 5) and N represents onefewer than the number of contact groups (e.g. N=3, in accordance withthe preferred embodiment).

The contact array polling process starts at 50. J is initialized at 52and at 54 the contact group corresponding to the current value of J isgrounded (e.g. by driving one of OUT1-, OUT2- OUT3-, OUT4- of FIG. 6 lowactive). At 56 K is initialized and at 58 is compared with J. The firsttime through the loop, K =J and so K is incremented at 60. Assuming thatK is not greater than N+1 (e.g. four), as determined at 62, K is againcompared to J at 58. This time, K>J and at 64 L is set to the logiclevel of the contact group corresponding to K. At 66 the current contactgroup's logic level (the logical complement of sense inputs IN1, IN2,IN3, IN4 of FIG. 6) is compared with a logic low. If it is not low(active), then steps 60, 62, 56, 58, 64 and 66 are repeated causing thelevels of successive contact groups to be read and compared.

When a low level is detected on one of the contact group sense inputsignals, at 68 the grounded contact group corresponding to J is allowedto float and the contact group corresponding to K is grounded, effectinga inter-contact group polarity swap or reversal as described above byreference to FIGS. 4 and 5. At 70 L is set to the logic level of thecontact group corresponding to J, i.e. one of the IN1, IN2, IN3, IN4sense input signals is read by microprocessor 36. If the logic level ofthis contact group represented by L is low, then the read, compare andif-low-then-swap steps again are repeated. If after the polarityreversal between the contact groups represented by J and K, the contactgroup corresponding to J is not a low logic level--despite the fact thatgrounding a first contact group (corresponding to J) caused a secondcontact group (corresponding to K) to go to a low logic level--thenthere is a condition of non-symmetric impedance between the two contactgroups that is indicative of engagement with one or more of the planarcontacts in each contact group by circuit coupling structure 20. Thus,at 78 it is assumed that code-producing IC 16 is operatively coupledwith code reader 20 and ID unit I0 is read and its identification codeis processed.

It will be appreciated that, after reading ID unit 10 and processing thecode read therefrom, polling of contact array 22a starts over at 52 withthe reinitialization of J and K. In this manner, contact array 22a ispolled repeatedly by grounding one of the four contact groups while theothers are floating and, if a low-impedance condition is foundtherebetween, the signals energizing the two groups are reversed todetermine if the low-impedance condition is linear or symmetric(indicating an incidental short between the two contact groups, whichmay be ignored if possible, e.g. by driving the contact groups betweenwhich there appears to be a short to the same high or low voltage or bymasking the effect of the apparent short on all contact group pairsother than a pair determined to be engaged by circuit coupling structure20) or non-linear or asymmetric (indicating engagement therebetween bycircuit coupling structure 20). When its presence is indicated, IC 16 bythe preferred method of the invention already is biased so that, inresponse to predetermined drive signal amplitude and timing, its storedidentification code can be read by microprocessor 36.

It will be appreciated that energizing and reading oftwo-operative-terminal IC 16 in accordance with its predeterminedprotocol is performed by driving/sensing the indicated pair of contactgroups via corresponding ones of OUT1-, OUT2-, OUT3-, OUT4- and IN1,IN2, IN3, IN4 (refer to FIGS. 3 and 5). Those of skill in the arts willappreciate that, because physical and electrical engagement between IDunit 10 and contact array 22a may be only momentary, the polling of theentire detector contact array--including reading of IC 16 when such isindicated--must be accomplished within a fraction of a second. Such iswell within the capability of conventional microprocessors operating atmoderate clock speeds. It will also be appreciated that, if an ambiguousforward- and reverse-impedance condition is detected between contactgroups, the preference might be to assume that circuit couplingstructure 20 is in engagement therewith and to proceed with an attemptto read an identification code therefrom in accordance with the protocolspecified for IC 16. If such is not successful, it fairly may beconcluded at least that there is no properly responsive circuit couplingstructure 20 properly engaged with contact array 22a in any one of theinfinite positions and orientations that will enable its code to beread.

Turning now to FIG. 7, some important aspects of the geometry andarrangement of plural contacts 28 within contact array 22a aredescribed. It may be seen that the arrangement of plural contacts 28 issuch that no contact in a given contact group 1, 2, 3, 4 (so-labeled) isadjacent another contact in the same group. By dimensioning contacts 28and the spaces 30 interposing them as described above by reference toFIG. 2, and by connecting contacts 28 in parallel to form four contactgroups 1, 2, 3, 4, it may be seen that there is only a minusculepossibility of positioning or orienting point contacts 18a, 18b of IDunit 10 in physical engagement with target contact means 26 withoutoperative electrical coupling between different groups of contacts 28 insuch a manner as to render ID unit 10 readable. Such improbablepositioning and orientation would correspond with a condition in whichone or both point contacts 18a, 18b were in engagement entirely withingaps 30 or entirely outside the perimeter of contact array 22a. It willbe understood that an alternative number of contacts 28 might begrouped, or that other grouped contact arrangements might be made, thatare effective in minimizing the number and size of these so-called "deadzones", thereby to maximize the sensitivity of code reader 20 to pointcontacts engagement by ID unit 10 without unduly complicating codereader 22, within the spirit of the invention.

The orientation of contacts 28 relative to the typically passing-motiontype of contact that is contemplated by the invention--especially in thecontext of a skier wearing ID unit 10 who makes what probably would besliding contact in what may be thought of as a wiper action--prefers thegenerally horizontal orientation of both dual point contacts 28 andplural planar hexagonal contacts 28 as indicated in FIGS. 1, 2 and 7,the latter orientation of which may be fixed by stationarily mountingcode reader 22 (which of course otherwise may be portable, as is ID unit10) in a desired location, e.g. at the entry to a ski lift. In otherwords it is preferable that an axis along which contacts of the samegroup are aligned be parallel with the axis along which axially alignedpoint contacts 18a, 18b are most likely to slide. This further decreasesthe possibility that engagement by circuit coupling structure 20 will goundetected by code reader 22, since any sliding motion will tendultimately to position point contacts 18a, 18b clear of such dead zonesand fully operatively within a given response zone pair 32 (refer toFIG. 2).

The methods of the invention now may be understood, in view of thepreferred embodiment described above. The invention provides anambi-orientational method for automatically interrogating, auni-directional, two-terminal, code-producing circuit such as IC 16 ofthe preferred embodiment. The method involves energizing two terminals,e.g. terminals 16a, 16b, of the circuit with a first signal pair offirst polarity, e.g. complementarily driving signals OUT1- and OUT3-such that one is low (active) and the other is high (inactive) toproduce a potential difference of a first polarity (positive ornegative) between contact groups 1, 3 with which is engaged circuitcoupling structure 20. The method next involves measuring the voltagedifference between the two terminals, e.g. by sensing the logic levelsof IN1, IN3, and comparing such difference with predetermined criteria,e.g. whether they are of the same or opposite logic level, to produce anindication regarding the mating orientation of the two terminalsrelative to such first signal pair, e.g. microprocessor 36 detects thatgrounding one contact group causes another to sense low but that thereverse is not true, and concludes that there is a non-linear orasymmetric impedance condition between the contact groups indicating thepresence of a reverse-biased IC 16.

The method next implicitly involves the determination whether themeasuring-comparing step indicates a mating orientation of IC terminals16a, 16b that is the reverse of a desired mating orientation in which IC16 can be read. This is because, in accordance with the preferredmethod, the determination that a nonlinear or asymmetric impedancecondition exists between the contact groups is performed by energizingcontact group pairs with such polarity and in such order that IC 16 isassurably reverse-biased when its presence is determined. The methodthus involves automatically energizing the two terminals of the circuitwith a second signal pair of reverse polarity from the first polarity,e.g. drive signals OUT1-, OUT3- are both complemented, or are energizedwith a reverse polarity signal pair, by microprocessor 36 such that theone which was previously high now is low, and vice versa. With IC 16 nowproperly biased, e.g. with a low level, or logic zero, (circuit groundreference) signal on one terminal and a high level, or logic one,(power/data) signal on the other, for normal operation, the final stepof the preferred method is performed by which two-terminal,code-producing circuit 16 is read in accordance with its device-specificread protocol. Thus, the method is described as being ambi-orientationalbecause it automatically can read uni-directional IC 16 in eitherorientation of ID unit 10 relative to a given pair of adjacent contacts28 of code reader 22.

The preferred method for scanning a plural contact array, responsive tophysical contact by a code-producing unit such as ID unit I0, now alsomay be understood. The method involves first energizing selected ones ofplural arrayed contacts at a first signal level, e.g. driving OUT1- low(active) effectively to ground contact group 1; and second energizingselected other ones of said plural arrayed contacts at a second signallevel different from said first signal level, e.g. driving OUT3- orallowing to it to float high (inactive) effectively to allow contactgroup 3 to be pulled up by resistor R3 to the level of V_(DD). Themethod further involves sensing the signal level difference between theselected ones and the other ones of the plural arrayed contacts, e.g.reading IN1, IN3, wherein the signal levels in accordance with thepreferred embodiment are either low or high and represent binary(boolean) values, and comparing the difference with a predeterminedvalue to determine whether the difference indicates physical contactwith code-producing unit 10, e.g. determining whether IN1 is high(active) and IN3 is low (inactive), wherein the difference in accordancewith the preferred embodiment of the invention is represented by alogical combination of binary (boolean) values and the comparison inaccordance therewith is with a binary (boolean) value. It will beappreciated that such sensing and comparing steps, within the spirit ofthe invention, may involve analog, rather than discrete, levels andvalues, e.g. by use of window comparators and associated analogdrive/sense circuitry.

The preferred scanning method next involves a determination whetherphysical contact, of the selected ones and the selected others of pluralarrayed contacts 28, with code-producing unit 10 is indicated, e.g. bythe detection of a nonlinear or asymmetric impedance condition asdescribed above and as illustrated by FIG. 6, and, if such is indicated,then determining whether energization of the first and other selectedones of contacts 28 is of a polarity which is predefined by IC 16 toenable the reading of a code therefrom. This is the step that isimplicitly performed as described above in accordance with the preferredembodiment and method whereby, for example, OUT1-, OUT3- arecomplemented to drive OUT1- high (inactive) and OUT3- low (active) andit is determined whether IN1 and IN3 track one another, level-wise,regardless of the polarity of the drive signal pair OUT1-, OUT3-(indicating a linear or symmetric, low-impedance conditioncharacteristic of an incidental short circuit), or whether instead IN1and IN3 track one another only given certain conditions on OUT1-, OUT3-(indicating a non-linear or asymmetric, low-impedance conditioncharacteristic of a non-linear device such as the integral diode of IC16).

The next step involves either reading the code from code-producing unit10 directly, in the case of the proper, predefined energizationpolarity, or first reversing the energization polarity, e.g. bycomplementing OUT1-, OUT3-, and thereafter reading the code fromcode-producing unit 10. If physical conduct between the selected onesand other selected ones of contacts 28 and code-producing unit 10 is notindicated, then the second energizing step and steps subsequent theretoare repeated, but this time with different selected others of the pluralarrayed contacts, e.g. by driving OUT4- or allowing it to float high(inactive), rather than OUT3-, to determine by sensing IN1 and IN4whether there is a low impedance condition between contact groups 1 and4 which indicates a properly biased IC 16 thereat. Finally, the firstenergizing step and steps subsequent thereto are repeated, but this timewith different selected ones of the plural arrayed contacts, e.g. bydriving OUT3- low (active), rather than OUT1-, to determine by sensingIN1 and IN3 whether there is a low impedance condition between contactgroups 3 and 1 which indicates a properly biased IC 16 thereat.

The applications and advantages of the invention are now readilycomprehended. The identification number which is read from ID unit 10may be sent to a central computer for verification (or may be processedat code reader site based upon previously downloading to the site therequired verification data) to determine whether the wearer thereof isauthorized to pass the checkpoint. For example, a skier wearing portableID unit 10 may be a season ticket holder, which authorization would beverified and the skier allowed to board a ski lift. On the other hand,the skier may be unticketed, and thus he or she may be an unauthorizeduser of the ski lift, in which case a indicator panel monitored by alift operator would indicate the attempted unauthorized access and thelift operator could prevent the skier from boarding the lift (suchaccess control instead might be automatic, e.g. by use of a lockableturnstile).

Other applications would include counting the number of times a skierboards a particular lift, which information might be interpretable bythe ski resort owner/operator as an indication of lift utilization,average downhill runtime, average and peakload use of lifts, etc. Suchinformation would be maintained in a database under control of theresort owner/operator, and might lead to future resort improvements,changes in daily and seasonal opening and closing times, grooming orredesign of certain runs, incidence of theft of services by unauthorizedusers, etc. Those of skill in the art will appreciate that numerousapplications of the invention are possible, whether ski related orotherwise. It is believed that the apparatus and method of the inventionprovide an unprecedentedly large-target area by which contact canreadily be made for identification, access control and monitoring ofpersons passing a checkpoint, while maintaining high sensitivity tomomentary or brushing contact thereby and a great tolerance forincidental adjacent-contact bridging, as by ice, water or even a strayfinger. The invention provides such advantages in a simple system, witha cost-effective apportionment of cost between high-volume ID units andrelatively low-volume code readers.

Accordingly, while preferred method and apparatus of the invention havebeen described herein, it is appreciated that further modifications arepossible that are within the scope of the invention.

I claim:
 1. A code reader system comprising:one unit including structuredefining an active sensor expanse having plural pairs of spacedexternal-circuit-couplable response zones; another unit interactablewith said one unit, said other unit including an external-circuitcoupler including a pair of spaced contacts engageable with saidexpanse; said other unit, in substantially any coplanar orientation ofsaid sensor expanse relative said spaced contacts in which each of itssaid contacts engages said expanse, effecting circuit coupling betweenat least one pair of said zone; and the length of said expanse in atleast one dimension being substantially larger than the distance betweensaid spaced contacts.
 2. An identification system comprising:at leastone identifying station including a response production expanseextending two-dimensionally to define a target area of said station, anda garment item wearable by a user of said station, said item includingcircuit-coupling means defining a contact area operative to complete acircuit when said circuit-coupling means is momentarily engaged withsaid expanse in any one of an infinite variety of positions relativethereto, thereby to effect identification of said item to said station;said defined target area of said station being substantially larger thansaid defined contact area of said item.
 3. A code reader systemcomprising:a first unit including a housing mounting code-producingmeans for producing a coded signal in response to an interrogationsignal pair, said first unit further including a pair of spaced pointcontacts operatively connected with said code-producing means, and asecond unit including a housing mounting code-reading means forgenerating an interrogation signal pair and for responding to said codedsignal, said second unit further including a generally planartwo-dimensional uniform array of plural contacts interposed by spacessuch that the surface area of said plural contacts substantially coversthe surface of said array and such that the distance from a given edgeportion of a first one of said plural contacts to a non-adjacentcorresponding edge portion of an adjacent one of said plural contacts isapproximately equal to said given spacing of said pair of spaced pointcontacts, said code-reading means producing said interrogation signalpair sequentially on adjacent ones of said plural contacts; whereby atleast momentary physical contact by said pair of spaced point contactsof said first unit with any adjacent ones of said plural contacts ofsaid second unit operatively couples said code-producing means with saidcode-reading means.